摘要:

The complete ovipositional rhythms ofThyanta pallidovirens(Stal) fed peas, beans, or lentils and the diel ovipositional rhythms when fed beans were determined in the laboratory. The ovipositional response of these insects was significantly affected by the food provided;T. pallidovirensthat were provided peas produced significantly more eggs ($\bar x$= 295) than those provided beans ($\bar x$= 165) or lentils ($\bar x$= 122).T. pallidovirensfed peas had constant eggs per clutch (E/C) and number of days between clutches (DBC) over the ovipositional period; whereas those fed beans or lentils had significant negative slope when E/C or DBC were predicted by either days from first oviposition or number of clutches already laid.T. pallidovirensthat were fed beans had a consistent diel ovipositional cycle with 1500 and 1700 hours having significantly more oviposition than 400, 1600, 1800, and 1900 hours, which were significantly greater than 200, 2200, 2000, 1400, and 2100 hours, which were significantly greater than the remaining hours. There was also a consistent diel mating cycle for this insect, with 400, 500, 600, and 700 hours having significantly more mating than 800, 900, 2200, 2100, and HOO hours, which were significantly greater than the remaining hours.

DOI:10.1093/ee/19.3.630

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

During a 2-yr study investigating the fecundity of the sugarcane borer,Diatraea saccharalis(F.), 607 pupae were collected on four gramineous hosts. Weight, length, and diameter of sugarcane borer pupae collected on corn,Zea maysL. cv. Merrit, and a sugarcane borer-susceptible sugarcane (a complex hybrid ofSaccharumspp.) variety, CP 61-37, were greater (P<0.05) than those of pupae collected on johnsongrass,Sorghum halapense(L.) Persoon. Female pupae collected on a moderately resistant sugarcane variety, CP 65-357, weighed significantly less (P<0.05) and were shorter than those collected on CP 61-37 or corn. The sex ratio of sugarcane borer was independent of host plant. The best model for predicting sugarcane borer fecundity was that of a linear regression on pupal weight, with fecundity increasing at 4.3 eggs for each milligram increase in pupal weight, regardless of host or year from which the pupae were collected. Fecundity of moths collected from corn and the susceptible sugarcane variety was greater (P<0.05) than that of moths collected from johnsongrass or the moderately resistant sugarcane variety. The potential finite daily rate of increase of sugarcane borer populations was determined to be 1.132 on corn and CP 61-37, 1.128 on CP 65-357, and 1.119 on johnsongrass.

DOI:10.1093/ee/19.3.635

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Experiments were conducted to determine the influence of the density and size of patches of soybeans (Glycine max(L.)) on the extent of pod damage by the lima bean pod-borerEtiella zinckenella(Treitschke). In addition, an evaluation was made of changes in rates of parasitism as a function of changes in patch characteristics. Low-density plots had a greater proportion of pod damage than did high-density plots. Plot size did not influence the proportion of pods attacked per plant. Larval parasitoids ofE. zinckenella, in general, were not influenced by plant density but were influenced by host herbivore density. Other experiments were conducted to determine if mixtures of soybeans with a feral host,Crotalaria pallidaAit, a species in the Fabaceae, would influence damage by the pod borer or parasitism. No differences were observed between mixed species plots and pureC. pallidaor pure soybean plots, in the number ofE. zinckenellalarvae per plant raceme nor in the level of parasitism. The abundance of pods produced by plants as a function of cultivar type, patch characteristics and time of season were also recorded.

DOI:10.1093/ee/19.3.640

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Two field releases of rubidium (Rb)-labeled, laboratory-reared adultPlatynota idaeusalis(Walker) were conducted to measure female adult dispersal and egg mass deposition patterns within a 33-ha (about 7,450 trees) apple orchard in Adams County, Pa. In both studies>3,200 virgin male and female adults (♂:♀ ratio = 1.1:1.0) were reared from rubidium-incorporated diet (3 g Rb/liter) and released on four center trees. Trees were randomly sampled for hatched and unhatched egg masses up to 500 m from the release sites. Atomic absorption spectrophotometry was used to detect rubidium in egg masses, and masses were considered marked if concentrations were>10 ppb. Following the first release, 417 trees were sampled and 39% of the 222 egg masses collected were marked. Following the second release, 260 trees were sampled and 67% of the 346 egg masses collected were marked. The distribution of rubidium-labeled egg masses demonstrated that spatial patterns of egg mass deposition are primarily local and are affected by ambient air temperatures. For example, 90% of all recovered rubidium-labeled egg masses were found within 65 and 45 m of the release sites, and the most distant labeled egg mass was found at 250 and 170 m, respectively, following adult releases during a warm period in July (daily minimum temperatures,>16°C) and a cooler period in September (daily minimum temperatures,<12°C).

DOI:10.1093/ee/19.3.648

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Distribution of pear psylla eggs on pear seedlings and cues affecting oviposition were monitored. Most eggs were deposited on the youngest foliage; few eggs were placed on the oldest, leathery leaves. Highest densities occurred adjacent to the midvein or in leaf serrations. Densities were very low on the leaf blade away from the midvein. Oviposition was induced in areas normally avoided (e.g., leaf blade) by providing strips of tape as artificial structures resembling midveins. Masking of particularly prominent midveins with strips of tape resulted in reduction of oviposition in these normally preferred sites. These results suggest that the midvein provided positive mechanical cues to ovipositing females. Effects of egg location on survival and development of eggs was quantified. Survival rates of eggs were higher for eggs deposited along the midvein than those deposited on the leaf blade. Survival decreased with increasing plant water stress. Development rates of eggs were not affected by location or stress.

DOI:10.1093/ee/19.3.656

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Higher mortality from nuclear polyhedrosis virus (NPV) was observed among gypsy moth larvae hatched from egg masses laid on virus-treated bark substrates than larvae hatched from egg masses laid on bleach-treated or untreated bark. Eggs from the inner portions of the egg mass (proximal to the substrate) were more heavily contaminated than those in the outer portions. These results indicate that gypsy moth egg masses can become contaminated with infectious NPV during oviposition on contaminated substrates. This mechanism may be an important mode of transmission in high-density populations or in years following an epizootic.

DOI:10.1093/ee/19.3.662

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

If soil factors at the time of hatch significantly influence the survival time of newly eclosed rootworm larvae or their ability to move through the soil to host roots, monitoring significant factors may provide an opportunity to improve predictions of economic damage. Survival time ofDiabrotica virgifera virgiferaLeConte was reduced at less than 100% RH and as temperature increased. Larvae moved farthest in loam soil with 24 and 30% moisture (−0.38 and −0.13 bars). Movement was restricted in wet soil (36%, or −0.05 bar) and in soil with 18% moisture or less. Larvae moved more than three times farther through silty clay or loam than through loamy sand. Movement through loam soil at a matric potential −0.38 bar was unaffected by bulk densities of 1.2 to 1.8 g/cc, and at least 5% of larvae moved to the farthest section of the test chamber at all bulk densities within 6 h under these conditions. Larvae survived for sufficient time in the soil to reach roots under most soil conditions. When soil is very wet or dry, increased mortality or decreased movement can reduce larval establishment.

DOI:10.1093/ee/19.3.666

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

A margarodid scale,Matsucoccus resinosaeBean&Godwin (=M. matsumuraeKuwana), and an adelgid,Pineus boerneriAnnand, are serious introduced pests of red pine,Pinus resinosaAiton, in parts of New England. Studies in a field plot revealed that both insects had significantly greater survival and fecundity onPinus resinosathan onPinus thunbergianaFranco, their native host in Asia. The performance ofP. boernerifeeding on both the branches and needles ofP. resinosawas significantly reduced by the presence ofM. resinosae, which fed only on the branches. The presence ofP. boernerihad no significant reciprocal effect on the fitness ofM. resinosae. Interspecific competition was a significant limiting factor forP. boerneri, and the needles did not provide a refuge from competition. In each of nine pine stands sampled in Connecticut, densities of adelgids and scales during a 7-yr period rose, but then fell sharply as trees became visibly injured. Abundance ofP. boernerion bark and on needles declined sharply in six pine stands following invasion byM. resinosae. In three of these stands,P. boerneriwas excluded by its competitor within 3 yr. Although competition occurred among these insects, it did not limit the growth of pest populations to a level at which the host could benefit from this antagonisitic interaction.

DOI:10.1093/ee/19.3.672

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Threecornered alfalfa hopper,Spissistilus festinus(Say), flight activity in alfalfa,Medicago sativaL., and diel activity in alfalfa and soybean,Glycine max(L.) Merrill, were monitored with yellow sticky traps and a rotary aerial sweep net. Movement was primarily within 33 cm above the soil surface. Amount of activity and numbers ofS. festinusincreased as alfalfa grew from stubble to harvestable plants. Activity was significantly greatest between 1000 and 1200 hours, during which temperatures averaged from 33.9 to 37.8°C. Limited flight occurred higher than normal during periods of greatest activity in alfalfa. Significantly more male than femaleS. festinuswere trapped on the sticky traps, contrasting with a more balanced sex ratio found in sweep net samples. Catches were apparently not affected by compass orientation of the sticky traps.

DOI:10.1093/ee/19.3.677

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Life tables are presented from six field populations of first- and second-generation southwestern corn borer,Diatraea grandiosellaDyar, infesting corn during a 3-yr study in the Texas High Plains. Survival from egg to adult was greater for first (0.20–0.52) than second (0.007–0.038) generation. Key-factor analysis identified egg mortality during first generation and large larval and diapausing larval mortality during the second generation as largely responsible for observed changes in generation survival. Stage-specific mortality for the first generation was predominately density-independent, and only negligible mortality was caused by natural enemies and intraspecific competition. Density-dependent mortality occurred in large larvae during the second generation. Intraspecific competition (cannibalism) and infection byBeauveria bassiana(Balsoma) Vuillemin were major second-generation mortality factors for large larvae and apparently were responsible for the observed density-dependent mortality. Adults developing from first-generation larvae on whorl-stage corn were significantly more fecund than second-generation adults developing as larvae on post-tassel-stage corn. The net reproductive rate was considerably greater during the first (Ro = 95) than second (Ro = 4) generation. Management tactics are proposed for reducing the economic effect of second-generation southwestern corn borer by suppressing the first-generation population increase.

DOI:10.1093/ee/19.3.684

出版商:Oxford University Press    

年代:1990

数据来源: OUP